Details of new Chinese plans to divert water from the Brahmaputra River emerged last month, causing expressions of concern to be made by Indian politicians from all parties.

The new plans involve the diversion of water from the Brahmaputra to the upper reaches of the north-western Chinese province of Xinjiang which has recently experienced serious droughts.

The plans follow the announcement in 2010 that China is building a hydroelectric project near the â€˜great bendâ€™ in the Yarlung Tsangpo, as the Brahmaputra is called in Tibet. The hydroelectric dam is the biggest in the world and will have an electrical capacity almost half that of the UK National Grid.

The Brahmaputra originates in south-western Tibet and flows through southern Tibet, breaking through the Himalayas and into Arunachal Pradesh in India. It flows south-west through the Assam Valley then South through Bangladesh. It merges with the Padma River in the Ganges Delta, before emptying into the Bay of Bengal.
The river is hugely important for irrigation and transportation in the region, and is highly susceptible to channel migration. The lower reaches are sacred to Hindus.

The level of apprehension in India is particularly high because of Chinaâ€™s level of secrecy regarding water flows. China refuses to enter into any water-sharing agreement with its neighbours and in the past major dam building and diversionary projects have only become public when spotted on satellite pictures of the region.

This secrecy makes it very difficult to assess the potential impact of the Chinese projects on the lower stretches of the river.

Any major diversion of the flow would lead to increased likelihood of droughts in Arunachal Pradesh and Assam in India, and in Bangladesh; lower silt carrying capacity and increased penetration of salt water into low-lying coastal areas will both be devastating for agriculture in Assam and Bangladesh.

On top of the threat to human livelihoods there is also a significant environmental threat.

The Brahmaputra is the lifeline for the Kaziranga National Park in north-east India which is home to two-thirds of the worldâ€™s great one-horned rhinoceroses, a large population of endangered Bengal tigers, a number of elephants and many other unique species which would come under threat if the river flow is impeded.

Any disruption to the flow of the river could also be catastrophic for the Gangetic river dolphins that call it home and are among the most threatened vertebrate species in existence.

The Chinese governmentâ€™s failure to provide the India with full details of its projects on the river, or to allow Indian experts to inspect the projects, makes it almost impossible to mitigate the effects of any changes which may happen.

The Indian government is seeking assurances from the Chinese authorities that the projects they are undertaking will not impact upon the water flow in India, and the UK government should support India in this.

River flows and water resources will increasingly become a focus of tensions and conflict in the region as we see the impact of climate change play out. That is why it is increasingly important that China signs up to a water-sharing agreement with India and Bangladesh, to provide a framework for solving any future conflicts in a responsible and co-ordinated manner.

I don't think it will be a catastrophe for NE India as many rivulets and streams join the Brahmaputra after it enters India and which contribute to its water level. The water in BP is enough for the limited agriculture that takes place in the North East.

The real catastrophe will be in BD as India will have the convenient excuse of China blocking out the waters to utilize the remaining waters for herself. It will be the Jamuna river in BD that will suffer from reduced water levels and creeping salinization that will destroy the farming of BD low lands.